What it does
"Hunt for Heresy" isn't actually a keyword or ability—it's a specific card name. Hunt for Heresy is a white Aura enchantment from the Modern Horizons 3 Commander decks (and originally Innistrad-flavored space) that you attach to a creature. While it's attached, that creature can't attack or block, and its activated abilities can't be activated unless they're mana abilities. Essentially, it's a "pacifism plus" effect that also shuts off problematic tap abilities.
The nuance people miss: it doesn't remove the creature, so abilities that trigger (not activated) still work, and static abilities still function. It also doesn't stop mana abilities, so a creature that taps for mana keeps doing so.
In Commander, it's solid cheap removal-lite for commanders you can't easily kill, neutralizing big attackers and combo-enabling tap abilities without giving the opponent a death trigger.
